News

Last week, the Flats Ecology and Conservation team downloaded data from a large-scale passive acoustic telemetry array designed to track bonefish to their pre-spawning aggregations. A total of 61 receivers were placed around Eleuthera to track the movements of 39 bonefish and 14 barracuda that were implanted with acoustic transmitters. The research team downloaded key receivers and found schools of bonefish moving over coral reef habitats at night near tidal creeks on the East coast of Eleuthera, indicating that these fish may move offshore to spawn on the windward side of the island. Stay tuned for more updates in June.

As a bonus, while collecting receivers the team got to swim by several Elkhorn coral (Acropora palmata) colonies, an IUCN-listed critically endangered species. Elkhorn coral grows rapidly, providing significant structure and habitat for reefs throughout the Caribbean, though it is in severe decline as a result of coral bleaching, predation, storm damage, disease, and human activity. Though it was heartening to see so many healthy colonies of this critically endangered species, they are small compared to the large stands of dead elkhorn that used to thrive in the area. Our reef restoration project has begun mapping these areas and will be monitoring its growth.

Last week the Reef Ecology and Restoration team completed the March monitoring surveys of the 5 year reef study around the patches of Eleuthera. The March surveys usually call for thick wetsuit, hoods and hot chocolate. However, the water was particularly warm at 27oC, resulting in the surveys being completed in record time. Dr Jocelyn Curtis-Quick has been leading this study since 2012; she now plans to use this incredibly unique and invaluable dataset to thoroughly examine the influences and impacts that the invasive lionfish have on the patch reef ecosystem.

The Reef Ecology team has already begun the process of analysis, and Jocelyn was able to present some of these preliminary findings at the Bahamas Natural History Conference in Nassau earlier in the month. By continuing to spread and enhance the local knowledge within Eleuthera and beyond, the management of the lionfish will hopefully continue to grow.

Of the 16 patches that have been surveyed throughout the study, 8 have been designated as removal sites, and with a highly experienced team we were able to continue our contribution to the culling effort around The Bahamas and wider Caribbean. Stay tuned to hear the full results of our study and a more detailed picture of how the lionfish is making its presence felt around Southern Eleuthera. In the mean time don’t forget, You Slay, We Pay!

Nassau grouper is an economically important species in The Bahamas. Due to heavy fishing pressure, there have been marked decreases in their population sizes, especially noticeable during their spawning season. The spawning season takes place during the winter months, from December to the end of February, and the aggregations occur during the full moon. Dr. Kristine Stump from the Shedd Aquarium has been monitoring Nassau grouper in The Bahamas to track their movements to spawning aggregations, as well as to quantify the number of Nassau grouper at these historical spawning sites.

This January, the Shedd Aquarium research vessel, The Coral Reef II, travelled to Long Island, to historical spawning sites, with a representative of The Cape Eleuthera Institute on board, to assist Dr. Stump with her research. Throughout the week-long journey, the researchers on board performed dive surveys to quantify spawning stock size at one specific site. Unfortunately, very few Nassau grouper were aggregating at the site during the times of the surveys; at most 20 were noted on one survey. Illegal fishing was occurring at the time the vessel reached the site, which could explain the decreased abundance of the grouper. Poor weather conditions prevented the researchers from performing surveys on the night of the full moon, so it is unclear if numbers increased during the spawning event.

Throughout the trip, amidst the dive surveys, Nassau grouper were implanted with transmitters. These transmitters track the movements of the Nassau grouper from the spawning sites back to their original habitat with strategically placed receivers, in efforts to understand where they come from and how far these fish travel to these spawning sites. At the spawning site, the five receivers were extracted and replaced with new receivers. The data from the receivers showed the movements of the Nassau grouper which will add to Dr. Stump's dataset. Blood samples were also collected from these fish for Krista Sherman from Exeter University, who is using this blood to look at hormone levels and ways of determining sex of grouper non-invasively.

Although the weather failed to cooperate, four fish were implanted with transmitters which will help provide data for the upcoming spawning period, and the receivers have provided Shedd Aquarium with useful data.

A spawning aggregation of thousands of bonefish (Albula vulpes) was recently filmed in South Eleuthera. Bonefish make monthly migrations of up to 80 km (50 miles) to form spawning aggregations!
https://www.youtube.com/watch?v=ikVNxeY2KRs&feature=youtu.be

CEI's Flats Ecology and Conservation Program is currently studying the spawning migrations of bonefish, which support a catch-and-release flyfishing industry worth over $141 million annually in The Bahamas. To view our most recent publications on this economically important species, please visit our website www.ceibahamas.org.

Previous research indicates that bonefish migrate up to 80 km from shallow flats and tidal creeks to deeper water to spawn during the full and new moons. At these locations, bonefish gather in schools of hundreds to thousands of fish, forming spawning aggregations. To date, migration corridors and spawning aggregations have been located in South Eleuthera, Abaco, Andros, and Grand Bahama, and this information was used to create national parks on Abaco and Grand Bahama. The purpose of this telemetry study is to identify bonefish spawning aggregations and migration corridors around the island of Eleuthera. Information generated by this research can be used by the Department of Marine Resources and BNT to designate marine parks on Eleuthera, which will help The Bahamas meet the goal of protecting 20% of their marine environments by 2020.

With the assistance of Dr. Karen Murchie (COB), Christopher Haak (University of Massachusetts Amherst), Dr. Liz Wallace (FWC), and Dr. David Philipp (FCF), 61 VEMCO acoustic receivers and 25 transmitters have been deployed around Eleuthera. Transmitters were implanted surgically into 25 anesthetized bonefish that were released at their capture location after fully recovering from the procedure. The receivers act as underwater listening stations, recording the date and time of any transmitter-implanted fish that swim past them, allowing researchers to locate migration corridors and spawning aggregations. This research would not have been possible without the support of local guides and businesses. Specifically, Zev Waserman of Rainbow Inn hosted the team for several days of fieldwork in North Eleuthera, and Manex Newton (Coco Loba Tours) and Denny Rankine (Eleuthera Island Fishing) provided boats and guided the team around Bottom Harbour and Savannah Sound, resulting in the successful tagging of 6 bonefish. The team plans to deploy 15 more transmitters by the end of January.